(1) Field of the Invention
The invention relates to the fabrication of integrated circuit devices, and more particularly, to a method for the formation of a capacitor during back-end processing whereby specifically are addressed concerns of capacitor breakdown and capacitor leakage.
(2) Description of the Prior Art
For many semiconductor devices, devices that are created for the purpose of operating in mixed mode of both logic and RF high frequency processing, high quality capacitors and inductors form an integral part of the created device. Digital and analog methods of signal processing may in this manner reside side by side in the same semiconductor device or package.
It is therefore not uncommon to see a mixture of electrical components and functions, comprising semiconductor devices, resistors and capacitors. The majority of semiconductor components consists of transistors, gate electrodes and a variety of switching components for the performance of logic processing functions. Capacitors may form a basic component of analog circuits in for instance switched capacitor filters. Capacitors are further widely applied in digital applications such as the storage node for Dynamic Random Access Memory (DRAM) circuits.
Requirements for the creation of high-frequency components such as capacitors and inductors include such aspects as low series resistance, low losses incurred in the component, high Q factor for a created capacitor, low RC time constants and the like. It is in addition desirable, for reasons of processing efficiencies and processing costs, to be able to create any reactive component such as a capacitor and an inductor as part of and integratable with the processing of a conventional semiconductor device manufacturing foundry.
One of the more common methods of creating a capacitor is the creation of a Metal-Insulator-Metal (MIM) capacitor, which finds frequent application in the creation of high-performance MOS devices that for instance are part of Random Access Memory (RAM) devices. Such a capacitor can have a sandwich or parallel plate structure. The bottom plate, of metal, is separated from the top plate, equally of metal, by a thin layer of capacitor dielectric. Both the top and the bottom plate can, for more modern capacitor fabrication processes, be made using a sequence of copper (for the bottom plate) followed by silicon nitride (for the capacitive dielectric) followed by copper (for the top plate of the capacitor). Copper however in this processing sequence is prone to the occurrence of surface irregularities such as copper hillocks, which leads to capacitor initial breakdown. These copper hillocks are further the cause of an unacceptably high level of capacitor leakage current, especially where silicon nitride is used as a material for the capacitor dielectric.
The conventional process of creating a capacitor in combination with the creation of a CMOS device is a relatively complex and therefore expensive process. This will further emphasize that the process of the invention, whereby a Metal-Insulator-Metal (MIM) capacitor is created that can be applied for mixed-mode applications, is a relatively simple and therefore cost effective method of creating a capacitor.
U.S. Pat. No. 6,274,435 B1 (Chen) and U.S. Pat. No. 6,300,682 B2 (Chen) shows a MIM capacitor and backend process.
U.S. Pat. No. 6,323,099 B2 (Long et al.) shows a Cu dual damascene capacitor.
U.S. Pat. No. 6,338,999 B1 (Hsue et al.) shows a TaN and Cu metal dual damascene capacitor process.
U.S. Pat. No. 6,329,234 B1 (Ma et al.) shows a Cu compatible CMOS MIM cap structure.